A major problem in secure communication systems is the possibility of unauthorized penetration. Unauthorized penetration of this kind is referred to as hacking.
Several methods have been employed to overcome the problem of hacking. Encryption of transmitted data and authentication of communicators are some of the methods employed to make hacking more difficult.
One hacking method which is considered difficult to overcome is called "The McCormac Hack". This method, which is believed to be theoretically applicable to CATV systems, is described in the book "World Satellite TV and Scrambling Methods", 2nd Edition, Baylin Publications 1991, pp. 243-244 by Frank Baylin, Richard Maddox and John McCormac and in "Satellite Watch News", August 1991. According to this method, a data stream from a legitimately authorized decoder, is extracted in real time and transmitted over the air using a small radio-frequency (RF) transmitter. The data stream is then used to activate a number of pirate decoders.